SOLUTION: A boat travels upstream 60 miles in 4 hours. The return trip going downstream takes 2 hours. Find the rate of the boat in still water and the rate of the current?

Algebra ->  Test -> SOLUTION: A boat travels upstream 60 miles in 4 hours. The return trip going downstream takes 2 hours. Find the rate of the boat in still water and the rate of the current?      Log On


   

Question 672207: A boat travels upstream 60 miles in 4 hours. The return trip going downstream takes 2 hours. Find the rate of the boat in still water and the rate of the current?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Boat speed =x mph
current speed =y mph
againstcurrent x-y 4 hours
with current x+y 2 hours

Distance = 60 miles distance= 60
t=d/r against current
60.00 / ( x - y )= 4.00

4.00 x -4.00 y = 60.00 ....................1
downstream
60.00 / ( x + y )= 2.00
2.00 ( x + y ) = 60.00
2.00 x + 2.00 y = 60.00 ...............2
Multiply (1) by 1.00
Multiply (2) by 2.00
we get y
4.00 x -4.00 y = 60.00
4.00 x + 4.00 = 120.00
8.00 x = 180.00
/ 8.00
x = 22.5 mph

plug value of x in (1) y
4 x -4 y = 60
90 -4 -90 = 60
-4 y = 60
-4 y = -30 mph
y = 7.5
Boat 22.5 mph
current 7.5 mph